Integration of distributed generation (DG) units and shunt capacitors in the radial distribution networks is one of the effective options that can be used to improve the system voltage and reduce system losses. Optimal sizing and siting of DG units and shunt capacitors need to be ensured for strengthening the supply quality and reliability of distribution systems. In this regard, new analytical strategies need to be devised to minimise the computational burden and improve the overall accuracy of the solution. In this paper, a numerical method for the identification of the target voltage support zones is proposed by reducing the large search space. The strategic placement of DG units and shunt capacitors is proposed for overall voltage support and power loss reduction in a distribution feeder. The investment cost for DG units and shunt capacitors is minimised by using particle swarm optimisation (PSO) technique.